[m-rev.] for review: Put .mh files into Mercury/mhs subdirectory.

[Zoltan Somogyi]

On Tue, 23 Jul 2024 14:32:47 +1000, Peter Wang <novalazy at gmail.com> wrote:
> compiler/file_names.m:
>     Replace ext_cur_mh with a new option in a new category,
>     ext_cur_ngs_max_cur_mh.

This wording implies that ext_cur_ngs_cur_mh is the name of the
new category, which it is not. I would say "Replace ext_cur_mh
with ext_cur_ngs_max_cur_mh, in the new category ext_cur_ngs_max_cur".

> compiler/write_deps_file.m:
>     Add $(mhs_subdir) prefix before %.mh patterns.
> 
>     Create a Mercury/mhs -> .. symlink when installing.

Do NOT do this, ever. It makes it impossible to back up
the resulting directory, because the cp command will copy
Mercury/mhs to the target location in an infinite loop.
In this case, it is too late, because this problem already exists
for other suffixes, but in other projects ....

>     Conform to changes.

.. to the changes above.

The rest seems fine.

However, this diff also raises a question. When I completely redesigned
file_names.m, I left the handling of each extension as it was before,
even when it did not make sense. There are a bunch of XXXs in that file
noting extensions whose old handling (which we have so far preserved)
seems wrong. The intention was always to fix these together, because
for users, a single big change is preferable to a drip-feed of smaller changes.
The question is: should we start this process now?

Zoltan.